Projectors configured to project an image are widely used in these years. It is desirable that a projection surface onto which to project an image be plane in order that the image projected from the projector may be easy to see. Against this background, proposal has been made on a technique for automatically detecting a projection range suitable for a projector to project an image.
An information projection display apparatus is known which uses two markers set on a projection surface and a pre-specified base angle to define, as a projection area, a rectangular area whose opposite corners correspond to the two markers.
Meanwhile, another information presentation apparatus is configured to: project a lattice-pattern image onto a work area using a second projector; capture the projected lattice-pattern image using an infrared camera; extract plane areas by comparing the captured lattice-pattern image and the original lattice-pattern image; detect the plane area which is the largest and closest to a square among the extracted plane areas; and project presentation information onto the detected plane area using a first projector. Prior art documents include Japanese Laid-open Patent Publication Nos. 2007-36482 and 2006-189712.